Hello R experts,

I have generated a data set below. I tried to export the object - my.pvalues (class is "by")

as .txt (or excel file), so the output in matrix form line up nicely in .xls file. Do I have to convert to some other data formats before using write.table? I am having difficulty to get this out.


I really appreciate it if anyone here could kindly guide me.

Kevin

##### Data   ####

a <- c(rnorm(6,mean=0.5,sd=0.1),rnorm(18,mean=4,sd=1))
b <- factor(rep(LETTERS[1:4], each=3, lenth=24))
grp <- rep(factor(c("WT","TG")), each=12)

d <- as.data.frame(cbind(a,b,grp))

my.pvalues <-by(d,
              INDICES=d[,"grp"],
           {
              FUN=function(x)
              pairwise.t.test(x$a,x$b)$p.value
           }
               )
class(my.pvalues)
[1] "by"


###  Results  ###

> my.pvalues
d[, "grp"]: 1
  1  2  3
2 1 NA NA
3 1  1 NA
4 1  1  1
------------------------------------------------------------ 
d[, "grp"]: 2
             1            2          3
2 0.7629610481           NA         NA
3 0.0006906049 0.0006059707         NA
4 0.0164179404 0.0141134949 0.03267941

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